Monthly Archives: August 2009

Making Friends with the Night Sky: The Full Moon

Lunar eclipses can occur during the full moon period

Lunar eclipses can occur during the full moon period

Maui astronomer Harriet Witt describes our full moon, and how the alignment of the Sun, Earth and Moon – syzygy – can affect the planet.

Listen here [3:08m]:

Download here [2.9 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090801_mfns-fullmoon.mp3

What’s the facts:

Halfway through our lunar cycle, the Moon and the Sun are now on opposite sides of the Earth, so we see a fully sun-lit full Moon.  At this time, the Moon rises as the Sun sets, and the Sun rises as the Moon sets.  This alignment of Sun, Earth and Moon is called syzygy (pronounced “SI-zi-gee“) and occurs during both new and full moon.  This alignment magnifies the ocean tides on Earth (both the Sun and the Moon cause tides through gravitational force), and the full moon is a time when lunar eclipses can occur, about once or twice a year.   Imagine standing on the Moon at this moment; you would see a “new Earth”, or the dark side of the Earth, up in the sky.  Similarly, you would see a “full Earth” during the period of new moon.   In many ways, full moon is a period of opposition.  It is also a period of celebration, with many holidays occurring during full moon in tradiational cultures, such as the Chinese Lantern Festival, the Hebrew Passover, and the Muslim Shab-e-Bara’at.  The bright night also inspires full moon parties.   Have fun celebrating our closest celestial neighbor!

This Astrofact is dedicated to Mahina, our four-legged full moon.

Original air date 1 August 2009.

Advertisements

Making Friends with the Night Sky: The New Moon

A glimpse of the moon through the trees, as it phases from new moon to cresent.

A glimpse of the moon through the trees, as it phases from new moon to cresent.

Maui astronomer Harriet Witt describes the new moon, the start of the lunar cycle.

Listen here [3:26m]:

Download here [8.1 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090722_mfns-moonnew.mp3

What’s the facts:

“A month is a Moonth, a Moonth is a moon.”  For many traditional calendars – Hawaiian, Chinese, Hebrew, Islamic – this is still true, although our western calendar has been tweaked to fit the months into one year.  The new moon is the start of the lunar month, and the time when the moon lies between the Sun and the Earth (this is called syzygy, a great Scrabble word).  Imagine yourself floating out in space well above the Sun, Moon and Earth, and you will see these three bodies in a row, with the Sun-lit side of the Moon facing away from the Earth.  So where is the new Moon in the sky?  Directly in front the Sun!

Why doesn’t the Moon block, or eclipse, the Sun every time the new moon phase happens?  It’s because the plane of the Moon’s orbit is actually inclined by about 5° relative to the plane of the Earth’s orbit (the ecliptic plane).  So most of the time, the Sun, Moon and Earth are out of alignment during new moon.  However, the Moon’s orbit actually rotates, or precesses, every 27.2 days.  So perfect alignment at new moon occurs about once every 18 years, a period the Babylonians called a Saros cycle (a complete explanation can be found here).  In fact, there are several Saros eclipse cycles because the Sun-Moon-Earth alignment doesn’t have to be perfect, so we get about two eclipses at new moon every year.

New moon is a great time for star-gazing as the Sun and the Moon will have both set in the evening.  So be sure to enjoy the dark skies that accompany the new Moon!

Original air date 22 July 2009.

Making Friends with the Night Sky: The Waxing Crescent Moon

The waxing crescent - the start of the lunar cycle

The waxing crescent - the start of the lunar cycle

Maui astronomer Harriet Witt describes the waxing crescent moon –  the first phase in the lunar cycle – and Earthshine.

Listen here [3:00m]:

Download here [7.3 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090722_mfns-mooncrescent.mp3

What’s the facts:

The waxing crescent is the first phase in the new Moon to new Moon lunar cycle.  You can catch it by looking toward the western sky early in the evening; there you will see a bowl-shaped sliver pointing toward the setting Sun, following it down to the horizon.  The opposite side is darker but not completely dark – it is faintly lit up by sunlight reflected from the Earth’s surface, called Earthshine.  The origin of Earthshine was first figured out by Leonardo Da Vinci in the 1500s; scientists now use Earthshine to track global cloud coverage and variations in the Earth’s climate. The waxing and waning crescent phases are the best time to observe Earthshine, so enjoy our spotlight on the Moon!

Original air date 22 July 2009.

Making Friends with the Night Sky: The Waning Crescent

The waning crescent appears on the left in the Northern hemisphere, and the right in the Southern hemisphere

The waning crescent appears on the left in the Northern hemisphere, and the on right in the Southern hemisphere

Maui astronomer Harriet Witt describes the “old” waning crescent Moon.

Listen here [3:30m]:

Download here [3.2 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090813_mfns-wanningcrescent.mp3

What’s the facts:

The waning crescent, or “old moon”, can be seen shortly before dawn, a thin sliver that rises ahead of the Sun.  You have a short period to catch it; after the Sun rises, the thin crescent is hard to see in the bright glare of day.  The waning crescent occurs toward the end of the new Moon to new Moon cycle, a siderial period of  27 1/2 days if you measure the Moon’s position relative to the stars, or a synodic period of 29 1/2 days if you measure relative to Sun.  The difference is due to the Earth’s motion around the Sun.  During a “moonth” the Earth has traveled about 1/13th of its yearly orbit (at a rate of 1.3 million miles per day).  So from our point of view, the Sun has moved to a different part of the sky relative to the stars – by about 28 degrees – over the lunar cycle.  Every month brings a new perspective!

Original air date 13 August 2009.

Spacetime!

Spacetime will suck up all your time...and space!

Spacetime will suck up all your time...and space!

Charae and Bryce take us on a trip into spacetime, with a song about everything they’ve learned from Astrofacts, to the tune of Rihanna’s Disturbia.

Listen here [2:50m]:

Download here [2.7 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090730_spacetime.mp3

What’s the Facts:

Charae & Bryce have put together a song that’s rich in astrofacts. Let’s break down the lyrics to see what they will encounter on their trip into spacetime.

Lyrics:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Neptune, Uranus, Plut-
Whao! Hold up. Not Pluto.
What?!? Not Pluto?
Yeah, Not Pluto.
I’m goin’ crazy now

Here’s our planets of the Solar System, up to Pluto, which has been “reclassified” as a dwarf planet.  Pluto might be feeling a bit down about it, and plenty of people are not happy either!  By the way, Neptune comes after Uranus, our mistake!

To the moon in this ship,
We’re gonna get it started,
Fuel tanks filled to the rim,
Discover the uncharted,
Breaking through atmospheres,
It’s not for the fainthearted,
We’re gonna go into space, yeah

Want to go into space?  Be prepared for an explosive ride!  You only need enough force to overcome Earth’s gravitational pull to go toward space – which you can do briefly by jumping!  But to sustain the upward trajectory requires lots of fuel and thrust.  The rockets that carry the Space Shuttle have a combined thrust of 13 million Newtons – 20,000 times the force you exert when jumping – to lift the 4.5 million pounds (2 million kg) that hold 7 lucky astronauts!

It’s real hot on the Sun,
Forgot my sunscreen,

It’s definitely hot on the Sun – 9,800 degrees Farenheit! That’s so hot that everything is essentially evaporized on the surface, and atoms are even stripped of their electrons to form a 4th state of matter called plasma.

The day’s long here on Mars,
I need some caffeine,

A day on Mars take 24 hours, 39 minutes, and 35 seconds – about 3% longer than that of Earth.  So it’ a little longer, but you’ll adjust.

2.9 times 10 to the 13
Miles a minute, I’m carsick.

That’s a pretty big number, and  one would hazard to guess that it’s the speed of light.  However, the speed of light is only about 11 million miles per minute.  290,000,000,000,000 miles is about 5 light-years, a little further than the nearest star to the Sun, Alpha Centauri.  If you could do that in a minute, you would certainly be carsick!

We’re in great heights,
In one of Saturn’s rings, yeah
You ain’t go bling like mine,
Meteors made for kings,
We watch the stars shine,
From Polaris to Betelgeuse,
The universe is mine.

Some of the most beautiful things in our Universe! Saturn’s rings are definite bling, comprised of small particles of water ice and dust that are extremely reflective – that’s why Saturn it so bright despite being further from the Sun than JupiterMeteors are of course another dazzling night sky event, while Polaris (the North Star, in the constellation Ursa Minor, or Little Bear) and Betelgeuse (in Orion’s armpit!) are two of the brightest stars in the sky.

We’re all in Space-time,
Two words in one continuum,
Space-time,
1, 2, 3, 4 Dimensions,
Your mind’s in Space-time
Beyond comprehension,
Space-time, Space-time.

Space-time is that idea of three-dimensional space (length, width and height) combined with one-dimensional time as the “framework” of the Universe.  You probably already think this way, as in “I need to get to the third floor of the building on the corner of Main and 1st Avenue at 3pm”.  These dimensions appear to be completely separate in our slow, small-scale world, but when you travel close to the speed of light, or near a massive object like a black hole, Einstein’s theory of general relativity tells us that the continuum of space and time can get mixed up, resulting in some bizarre effects!

There’s a guy in the sky,
His names Orion,
Not a man, he’s made of stars,
Emitting carbon.

This refers to the massive giant star Betelgeuse in Orion, which is currently losing mass and size as it sheds its outer atmospheric layers.  It will eventually supernova, releasing many elements such as carbon into space.  It is all part of the cycle of life in the Universe, as the elements shed from stars like Betelgeuse when they die make their way to form other stars, planets and even people!

Acid rain falls,
It burns my eyeballs.
Venus lighting strobe light.

Remember our weather report from Venus?  Acid rain doesn’t quite make it the surface of the planet, but there are plenty of lightning strikes that might make the surface of Venus feel like a disco!

Lots of holes out in space,
They try to grab you,
They can creep up behind you and consume you,
Not even light can escape,
Nothing can breakthrough,
Spa-ghe-tti-fi-ca-tion.

Black holes are the massive remnants of stars that are so dense that nothing, not even light, can escape being swallowed up. If you’re not careful you’ll get pulled into it and never come out again.  And on the way in you’ll get stretched out long and slender, like spaghetti. That’s called spaghettification!

We’re in great heights,
In on of Saturn’s rings, yeah
You ain’t go bling like mine,
Meteors made for kings,
We watch the stars shine,
From Polaris to Betelgeuse,
The universe is mine.

We’re all in Space-time,
Two words in one continuum,
Space-time,
1, 2, 3, 4 Dimensions,
Your mind’s in Space-time,
Beyond comprehension,
Space-time, Space-time.

Lyrics by Charae and Bryce

So you think you can orbit?

Pluto & Charon do the perpendicular binary hip-hop

Pluto & Charon do the perpendicular binary hip-hop

Pluto and Charon dance it off in the intergalactic smash hit “So you think you can orbit?”  Can their perpendicular orbit help them win it all?

Listen here [2:02m]:

Download here [1.9 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090813_soyouthinkyoucanorbit.mp3

What’s the facts:

Pluto, the second-largest known dwarf planet in the Solar System (after Eris), and its largest moon, Charon, are sometimes treated as a binary system, because the center of their orbit does not lie within either body (Charon is about half as big and 1/7th as massive as Pluto).   Indeed, before its re-classification, Pluto and Charon were the closest thing to a double planet known.  The orbit of Pluto and Charon is also special in that it is nearly perpendicular to the plane of their mutual orbit around the Sun, like a record rolling on its side (Uranus and its moons are tilted over in a similar way).  As such, the Pluto-Charon orbit can be seen either face-on – like a clock – or edge-on – like a thrown frisbee – during its 248-year trek around the Sun. Between 1985 and 1990 the orbit was aligned edge-on so that the two bodies repeatedly passed in front of each other, or eclipsed.  These eclipses allowed astronomers to measure both the sizes of Pluto and Charon as well as make a rough map of Pluto’s surface features.  Finally, Pluto and Charon are the only planet-moon pair whose orbit and rotations are mutual synchronized; that is, they both face the same face to each other all the time. This makes Pluto and Charon excellent partners as the dance their way through space!

Original air date 13 August 2009.

Making Friends with the Night Sky: The Gibbous Moon

The moon entering its gibbous or hua phase

The moon entering its gibbous or hua phase

Maui astronomer Harriet Witt describes the waxing gibbous Moon.

Listen here [3:30m]:

Download here [2.6 Mb]: ftp://space.mit.edu/pub/ajb/radiopio/astrofacts_090801_mfns-gibbousmoon.mp3

What’s the facts:

Progressing from the first quarter, the Moon enters its waxing gibbous phase, on the way to full bright moon.  The Moon is showing more of its sunny side to us on Earth, and is taking on an egg-like shape.  That’s why Hawaiians call the gibbous phase (gibbous is derived from the latin word “gibbus”, or “hump”) the “hua” or “egg” phase.

Original air date 1 August 2009.